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Sansa e200 - wheel light fade in/out, also display fade in/out

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seani:

--- Quote from: JdGordon on November 07, 2007, 08:27:57 AM ---I said...
the light is either on or off.. there is no hardware dimming possible..
it can be done in software but its not going to be added because im all honesty.. its stupid.

--- End quote ---

Just not quite as stupid as this sort of response to a polite request.

DB1BMN:
Hello,


--- Quote from: casainho on December 16, 2009, 05:36:36 AM ---Are you able to make that code?

--- End quote ---
Yes I hope so. I am familiar to assembler programming for 8051 Microcontroller and C language for PC and microcontroller and bought an Cortex M3 (Arm7) dev-bord a few weeks ago.
If you would give me a guide this would be grate!

The Lyre-Projejt I took a short look at it, I was also concerning about the Beagle Board or Pandora Console as a toy for the bored engineer but finally I ended up with the Sansa e200 and Rockbox for the moment.

Ok, for this time the measurings (of course the LEDs ar switched ON):
* voltage drop above blue LED: 2.98 V
* open circuit voltage after removing LED: 3.3 V
* short circuit current: 66.5 mA

The resistor value is 47 Ohms as I mentioned, this is nearly the same value as you divide 3.3 V / 66.5 mA = 49.6 Ohm, as there is some tolerance and additional resistance from the transistor Q9 ([AE2A] 1R = MMBT5089, npn, V_ce = 25 V, I_c = 100 mA, datasheet: http://www.datasheetcatalog.org/datasheet/fairchild/MMBT5089.pdf) which is common for all cathodes.
From the voltage drop of 0.3 V above the resistor I calculate approx. 7 mA I_F for each LED.
Can this be true that the Diodes can achieve such high brightess at this relatively low current? I did not measure the curren directly yet.

Pictures will follow later on evening.

Regards, Marek

casainho:

--- Quote from: DB1BMN on December 16, 2009, 12:27:57 PM ---Hello,


--- Quote from: casainho on December 16, 2009, 05:36:36 AM ---Are you able to make that code?

--- End quote ---
Yes I hope so. I am familiar to assembler programming for 8051 Microcontroller and C language for PC and microcontroller and bought an Cortex M3 (Arm7) dev-bord a few weeks ago.
If you would give me a guide this would be grate!

--- End quote ---
So you should no need for such a guide ;-) -- maybe you could do what I should on that time -- share the Rockbox firmware file with the wheel light dimming....

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